;= ex1a.asm ====================================================================
;
; Copyright (C) 2003, 2004 Nordic Semiconductor
;
; This file is distributed in the hope that it will be useful, but WITHOUT
; WARRANTY OF ANY KIND.
; 
; Author(s): Ole Saether
;
; DESCRIPTION:
;
;  Hello World program.
;
;  The functionality is the same as in ex1c.c.
;
; ASSEMBLER:
;
;   You need as31.exe to assemble this program. It can be downloaded from this
;   web page: http://www.pjrc.com/tech/8051/
;
; $Revision: 4 $
;
;===============================================================================
           .equ  CKCON, 0x8e
           .equ  P0_DIR, 0x94
           .equ  P0_ALT, 0x95
           .equ  P1_ALT, 0x97
           .equ  CK_CTRL, 0xb6

           ljmp  start

start:     mov   TH1, #243       ; 19200@16MHz (when T1M=1 and SMOD=1)
           orl   CKCON, #0x10    ; T1M=1 (/4 timer clock)
           mov   PCON, #0x80     ; SMOD=1 (double baud rate)
           mov   SCON, #0x52     ; Serial mode1, enable receiver
           mov   TMOD, #0x20     ; Timer1 8bit auto reload 
           setb  TR1             ; Start timer1
           orl   P0_DIR, #0x02   ; P0.1 (RxD) is an input
           orl   P0_ALT, #0x06   ; Alternate functions on pins P0.1 and P0.2

           mov   dptr, #msg
           acall puts
loop:      ajmp  loop

puts:      mov   a, #0
           movc  a, @a+dptr
           jz    puts2
           acall putc
           inc   dptr
           ajmp  puts
puts2:     ret

putc:      jnb   TI, putc
           clr   TI
           mov   SBUF, A
           ret

msg:       .db   "Hello World!\n", 0